The clamping force of the headphone is a key factor for the product designers to improve the ergonomics while wearing over head. Two different materials (PVC & Polypropylene) are being tested on the static structural solver to determine the reaction force (Clamping force) and the Von Mises stress acting on the material.
Design Optimization & Meshing:
The following CAD model was a courtesy of GrabCAD member Ghazi Chaabane.
Fig 1. Headphone CAD model
Since, the headband is the only component that creates the clamping force when inserted over head, all other components are neglected and the headband alone is uploaded to the Simscale platform as an IGES file. The meshing was done using automatic tetrahedralization of 2nd order coarse elements and shown below.
Fig 2. Meshing
After successful meshing, a linear static structural simulation is performed on the model. The model is setup in such a way to simulate the real-world testing environment, where one end of the headband is held in movable jig and the other end is stretched. The boundary conditions are set on the one end of the headband with a frictionless support that are constrained in X and Z directions, but can move in Y direction. On the other end of the headband, a displacement load of 0.08m is applied at -Y direction. A direct solver (MUMPS) is used. The displacement, reaction force and Von Mises stress is calculated for this simulation setup. The same conditions are employed for both materials, namely PVC and Polypropylene.
The following picture shows the change in shape before and after the displacement load is applied.
Fig 3. Representation of deformation
The following image shows the comparison of clamping force of both materials. It is found to be 5.219 N for Polypropylene and 15.65 N for PVC. The maximum impact is on the edges of the headband where the boundary conditions and displacement loads are applied.
Fig 4. Clamping force Polypropylene (left) and PVC (right)
The von Mises stress distribution is shown in the following picture.
Fig 5. Von Mises Stress Polypropylene (left) and PVC (right)
From the results of simulation, it is seen that in order to have reduced clamping force when the headphone is inserted overhead, the product designer is suggested to use Polypropylene plastics.